Effect of exogenous luteinizing hormone-releasing hormone on hypothalamic pituitary function in women with ovarian...

Pituitary luteinizing hormone (LH) pulse frequency and amplitude were assessed as an indirect indicator of hypothalamic luteinizing hormone-releasing hormone (LH-RH) release in women with evidence of ovarian failure. Exogenous LH-RH (20 micrograms) was administered intravenously every 2 hours for 48 hours to determine the effect on pituitary LH release and the hypothalamic pulse generator for LH-RH secretion. This study design was used to investigate the possibility of an ultrashort negative feedback of LH-RH upon the synthesis and release of endogenous LH-RH. A wide range of LH pulse frequencies (8 to 28 pulses/24 hours) was present in these women. There was no discernible inhibition of hypothalamic LH-RH pulse frequency during or following exogenous LH-RH administration. Mean peripheral LH levels were significantly increased during exogenous LH-RH administration (P = 0.0038), reflecting both an increased baseline and an augmented pituitary LH response to the exogenous LH-RH. There were no differences found in LH pulse amplitude before and after LH-RH treatment. These data indicate that pituitary LH secretion in women with ovarian failure can be further stimulated by exogenous LH-RH. However, there was no evidence for inhibition of either pituitary LH secretion or hypothalamic LH-RH release using this administration schedule of exogenous LH-RH.